In a production well, a production string composed of production tubing and other completion components transports production fluid from a downhole formation to the surface of the well. The production tubing is typically pressure tested to insure that no leaks will form under the pressure of actual production. It is desirable to find leaks before production fluid is introduced into the tubing because post-production repairs are grossly inefficient.
Typically, a temporary well barrier, or temporary plug, is used to seal off a particular segment or zone of the production tubing for pressure testing. Often, the well zone for pressure testing consists of essentially the entire tubing string. Fluid is then introduced above the temporary well barrier and pressurized to detect leaks in the production tubing.
In addition to testing for leaks, temporary well barriers can be used to set various types of hydraulically-activated tools on the tubing string. In this case, the barriers plug the tubing string to hold fluid pressure, which can then be applied to the hydraulically-activated tools. Either way, after testing or setting, the temporary well barriers must be removed from the production string so production can proceed.
As background to the present disclosure, FIG. 1A shows a tubing string 12 disposed in a well 10. A temporary well barrier 30 on the tubing string 12 can be used to test for leaks or to set hydraulically-set tools, such as packers 16, sleeves 18, and the like, on the string 12. The temporary well barrier 30 provides a temporary obstruction so that hydraulic pressure applied down the tubing string 12 from a pump system 25 at the rig 20 can be prevented from communicating further downhole.
In FIG. 1A, the barrier 30 is disposed at the toe of the tubing string 12, but this is not strictly necessary. Various barriers 30 can be disposed elsewhere along the tubing string 12. In fact, because temporary well barriers can be used to activate tools on the tubing string 12 with applied pressures, one or more barriers 30 can be disposed directly downhole from a hydraulically-set tool, such as a packer 16 or the like.
Several types of temporary well barriers can be used to test the tubing or to set hydraulic-set tools on the tubing string. Some of these prior art barriers include the Model WE Hydro Trip pressure sub by Baker Oil Tools, the OCRE Full Bore Isolation Valve and Multi-Cycle Tool by Baker Oil Tools, and the Mirage Disappearing Plug from Halliburton.
Some temporary well barriers use valves to control well flow, while others use dropped balls, frangible barriers, or other features. One type of temporary well barrier typical of the prior art includes a solid barrier held in place by a support assembly. To remove the barrier, the support assembly is retracted or sheared off to allow the solid barrier to drop through the wellbore. Once the temporary well barrier is removed, it is often desirable that substantially the full inner diameter of the production tubing is restored.
As one example, FIG. 1B shows a prior art well barrier 30 having a seat 34 temporarily held by shear pins 36 in a housing 32, which couples at its uphole end to tubing string (not shown). A dropped ball B engages the seat 34 to close off fluid pressure uphole. At a predetermined pressure, the seat 34 can be sheared free to open fluid communication and remove the temporary obstruction. This design may have limited use and may not be best suited for a horizontal wellbore.
To extend well-isolation to horizontal wells, temporary well barriers have been developed that provide a large bore after removal of the temporary obstruction without dropping the temporary obstruction into the wellbore. These temporary well barriers are broadly referred to as disappearing plugs. One type of disappearing plug operates by recessing the temporary obstruction into the housing of the device.
One disappearing plug from Baker Oil Tools, for example, recesses a flapper into the device where the flapper is then isolated from the production flow path. Other disappearing plugs operate by disintegrating a frangible well barrier, typically by impacting the barrier or setting off an explosive charge. Total Catcher Offshore AS in Bergen has developed several temporary well barriers employing this type of plug, such as the Tubing Disappearing Plug (TDP), the Tubing Disappearing Smart Plug (TDSP), and the Intervention Disappearing Smart Plug (IDSP).
For example, FIG. 1C shows a prior art temporary well barrier 30 having a frangible barrier 38 held in a housing 32 of the device 30. The frangible barrier 38 can provide isolation in both directions. Increased uphole pressure to a threshold or impact from above by an object (not shown) can break the frangible barrier 38 and open fluid communication through the housing 32.
U.S. Pat. No. 6,076,600 describes a plug apparatus having a dispersible plug member and a fluid barrier. In another example, U.S. Pat. No. 6,026,903 describes a bidirectional disappearing plug which is capable of selectively blocking flow through a flowbore of a tubing string disposed within a subterranean well. The plug may subsequently be disposed of, leaving little or no restriction to flow through the flowbore, and leaving no significant debris in the flowbore by causing a rupture sleeve to penetrate the plug member and destroy the plug's integrity.
Although the various temporary well barriers available in the art can be effective, operators are continually seeking temporary well barriers that can meet the various needs found in wells. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.